42. Squashed by the Pyramid

An occasional theme of this website has been food – who eats what – and the relations between our diet and the treatment of animals. I’ve just finishing reading a book about food and the recent history of dietary science and advice, especially in relation to fat, Nina Teicholz’s The Big Fat Surprise.

Early in the book I was reminded of a day, or more exactly, a moment, in 1998 or so. In the years leading up to that time I had tried hard to eat healthily according to the government-approved guidelines of the day. That meant a high carbohydrate and low fat diet. The advice was to get a half to 70% of calories from carbohydrates, some protein, and a bit of fat, but to avoid saturated fat as much as possible. A “food pyramid” summarized the guidelines. Above is the pyramid endorsed by the USDA between 1992 and 2005, (with dates via Wikipedia). The pyramid has a base, the largest slice, comprised of bread, pasta, rice, and so on. “Added” sugars are to be avoided, but you’re supposed to eat a lot of other carbohydrates.

I followed this advice with some care through the 1990s, and my health began to steadily decline, especially with respect to energy levels and overall sense of well-being. I had spectacular afternoon “crashes” for no apparent reason. I tried to get a lot of exercise and kept following the advice of the experts as well as I could. One day around 1998 I was driving along – I can remember the exact place, on El Camino in Redwood City, California – someone started talking on the radio, and I looked at the radio and thought: My God, they’re talking about me. An author was being interviewed about the “Zone” diet, one of the first unorthodox low-carbodydrate diets, and one that completely rejected the pyramid. It was not as extreme as some of those diets of the day (like the “Atkins” diet), and it was also complicated and fussy. But the Zone advocate was describing exactly how I’d been going downhill, and blamed it on all those carbohydrates.

Right away I began experimenting with diets that went against the rules – not applying the Zone or any other book-based diet, but simpler things. The change that had the biggest effect was to eat no, or almost no, glucose between breakfast and dinner. Fruit seemed fine, and it usually has a little glucose, but fruits like apples contain mostly fructose, which has a different pathway in the body. So no “starch” of any kind, and no refined sugar, after breakfast and before dinner. Breakfast was now big, with eggs, dinner smaller than before, with somewhat more protein and fewer carbs. This had an immediate effect. Before long I was fine, and ever since that time I’ve harbored a certain degree of anger towards whoever erected the 1990s pyramid and its high-carb regime. I thought: perhaps it is good for some people, but it made a mess of me, and my situation was only fixed by ignoring the experts.† This always felt odd for a philosopher who takes a scientific consensus seriously.

Teicholz’s fat book walks us back through those times, starting in the early 20th century and covering, decade by decade, how nutritionists in the US came to believe that fat is bad for you, especially saturated fat, and advised that a “prudent” diet should strip out a lot of fat and also a fair bit of protein, replacing these with carbohydrates. The book has its excesses and some weak moments, but its best passages are devastating. It is especially good in charting how the confident beliefs of a few people in the 1950s gave rise to a consensus, supported by government bureaucracies – and eventually by a lot of money from food companies, though that came a bit later. She is also very skilled in a describing the dietary establishment’s resistance to change as awkward data began to accumulate.

(I finished Teicholz’s book and wrote this post on the way to Bordeaux, France. Above is a detail of a magnificent group of statues at the Place des Quinconces. I’ve had a few seahorses on this website before, but none like that.)

If it’s true that the 20th century consensus on these issues was a mistake, it is important to ask whether this was an “ordinary” wrong turn in science, or a consensus of a special kind, one with features we can look for and guard against in other ongoing cases. Part of the problem was the intrusion of food-industry money, which in some cases appears to have been genuinely corrupting,* but that was perhaps not pivotal or necessary, especially in the early days. Another part of the problem was the role of some charismatic individuals who were sure they were right, and were also sure they were doing good. A particularly important element seems to have been an interaction between an urgently felt need for a solution to the growing problem of heart disease in the US, and what became an intuitive and even aesthetic appeal in the new rules. The picture of fat and oil as unclean and clogging, carbs as gleaming and clean (especially the “complex” carbs of later incarnations of the recommended diet) was powerful. In retrospect, the intuitive/aesthetic side ought to have been a prompt to caution, but there seems to have been none of that. Even I, wrecked by the carbs and salvaged on El Camino, still find it hard to think differently about those foods.

When you look at US government websites now, you have the sense that they’re no longer keen to give specific recommendations. The pyramid has gone (diluted in 2005 and abandoned in 2011), replaced by the vaguer “MyPlate” and plenty of encouraging but unspecific verbiage. I have a feeling that the people writing this material suspect there was a serious wrong turn in the last century, don’t really know what we should be eating, but are reluctant to admit it.

All this has also posed a difficult ethical problem for me. In abandoning the high-carb rules and eating more protein and fat, it becomes harder and harder hard not to increase the amount of animal food in one’s diet. I have moved away from being someone whose goal was to push at least a fair distance towards a vegetarian or vegan diet,** to someone who eats a lot of animal products but tries to make a big deal of the distinction between foods with a lot of cruelty behind them and foods that I think are OK. I’ve written about that distinction several times before on this site. One of the weakest aspects of Teicholz’s book is her consideration of these other factors in dietary choice, both ethical and environmental. The problem is not so much the tiny amount of space given to them. Teicholz says at the very end that her goal was just to look at the question of health, and leave other considerations aside. That would be fine, except that it’s not really what the book contains. She does advocate eating more animal food, with two reasons given (p. 334). First, the food is healthier than you think, and second, it’s “delicious” and “deeply satisfying.” Those things might be true, but they are not the only factors. Suppose veal, for example, was particularly healthy and particularly delicious; are those the only things you want to think about in the case of veal? Surely not. The lives of the animals are also part of the picture. The same issues apply, to a lesser or greater extent, to all animal-derived food.

Setting the ethical issue aside, looking at Teicholz’s book and tworecentNew York Times stories, it would be good to see someone from the other side, the side of the late 20th century dietary establishment, write something very frank about this issue – someone who’ll either point to the best data that shows the critics are misguided, or admit that a long generation’s worth of work was wrong. I suspect there are quite a few people like myself, who were squashed by the pyramid.

__________

Notes:

* The quote below is from the New York Times, September 12, 2016. It’s about some recently discovered documents.

In 1965, Mr. Hickson enlisted the Harvard researchers to write a review that would debunk the anti-sugar studies. He paid them a total of $6,500 – the equivalent of $49,000 today. Mr. Hickson selected the papers for them to review and made it clear he wanted the result to favor sugar.

Harvard’s Dr. Hegsted reassured the sugar executives. “We are well aware of your particular interest,” he wrote, “and will cover this as well as we can.”

Hickson was a sugar industry executive. Hegsted, who is discussed a lot in Teicholz’s book, was an important figure in the low-fat, high-carb movement. The new material in the Times story is more explicit and damning than anything Teicholz uses.

† A non-revolutionary shift in thinking is seen in the recent emphasis on glycemic index (GI). Was I eating too many high-GI carbs in my unhealthy days? Probably, but a shift away from them (to whole-grains, and so on) did not make much difference.

** I don’t make much of the distinction here because dairy farming, especially in modern forms, has always seemed one of the more troubling cases to me.

*** Nutrition Australia has kept a pyramid and flipped the lower two layers – fruit and vegetables are now on the bottom and grains just above.

Update, September 20:

Gina Kolata, the New York Times science writer, has just written an article about one of the Times’s recent low-carb articles, a commentary which recommended a low-carb diet for type 2 diabetes. (Kolata features briefly in Teicholz’s book as a defender of high-carb orthodoxy.) She quotes a diabetes doctor talking about diet in an interview:

“When you look at the literature, whoa is it weak. It is so weak,” Dr. Kahn said in a recent interview….

But people want diet advice, Dr. Kahn reasoned, and the [American Diabetes] association really should say something about diets. So it, like the National Institutes of Health, went with the Department of Agriculture’s food pyramid.

The Kolata article pushes back against recent low-carb proposals, not because there is data showing that the high-carb approach is better, but because there is no firm evidence showing long-term benefits for either diet, though there is some evidence showing short-term benefit for the low-carb diet. What matters most, according to the people interviewed in her article, is keeping weight down, and all diets tend to have compliance problems. This is not exactly a ringing endorsement of high-carb orthodoxy.

4 Responses to 42. Squashed by the Pyramid

The genus Homo evolved the way it did, mostly because hominids ate meat. Bipedalism evolved to enable hominins to cover large distance economically in the savannah (probably initially to scavenge, find far-away water and nourishing tubers). Bipedalism also enabled hominins to carry weapons (sticks and stones, as baboons and chimp also do, but not as well).

This evolution lasted seven million years, at least. Technology (the deliberate making of tools and clothing) is at least 3.4 million years old (probably from Kenyanthropus platyops or Australopithecus afarensis). The oldest tool activity known was cut marks on animal bones. And this cruel, yet nourishing activity predated the rise of a big brain found to start later with Homo Habilis. Conclusion? Hunting and eating meat was probably a cause of the creation of humanism.

And everything indicates that meat eating and the ability to kill animals, especially large animals, was the condition sine qua non of the human species. (In the past, for millions of years, massive, extremely ferocious megafauna had to be taught to respect human beings, otherwise hominins would not have existed.)

Million of years eating meat can only have changed human beings to the point they are genetically adapted to meat eating (even grazers such as cows eat small animals such as insects, snails, worms as they graze).

By contrast massive carbohydrate eating appeared in the last 12,000 years. Thus we are not evolutionarily adapted to it. In North America, massive corn planting and eating brought a greater population (from more calories), yet relatively degenerated (eating too much corn led to malnutrition).

True, Neanderthals ate vegetables, and cooked them. But in relatively small quantities.

I am not an anthropologist, but I have some doubts about this reasoning. I agree there are probably lessons in our history, but I doubt they are so simple and sweeping.

First there’s a question of principle: how informative is our deep history about which diets are healthy now? Historically novel diets could be fine. For example, I take it that the eating of fish such as salmon, with a lot of omega-3 fatty acids, was probably a latecomer in human evolution. But with respect to health, this is a good choice – better, I take it, than lots of more traditional foods, especially when what counts as “traditional” is taken to run so far back (millions of years). New diets need not be bad; they should be assessed case-by-case.

Second, the claim that “carbs” are not historically normal food for humans tends to conflate very different cases. Though eating grains might be novel, I take it that fruit is an old and very important food source for primates, probably for many of our ancestors. Some anthropologists claim that in traditional small-scale societies, while hunting is culturally prominent, a lot of the actual food available is gathered, by women, rather than hunted, and often takes the form of tubers (vegetable underground storage organs) and the like. Making a lot of noise about hunting prowess is one thing; getting enough to eat day-to-day is another.

As I said above, I agree there are lessons somewhere here in the history, but I’d express them more cautiously.

I read this thought-provoking post with some concern. There are two main reasons for this:

1. Balance: feeling good versus long-run health

2. Balance: personal perspectives versus systematic science

For the first issue, I’d be worried that readers may get the impression that eating lots of animal products is going to be good for their long-term health. There is still a lot of evidence that major causes of human mortality (cancers and heart disease) are strongly linked to the consumption of animal products, especially red meat (even lean red meat). And as the update to the post shows, it’s still immensely unclear whether there are long-term benefits to low-carbohydrate diets. It’s great to hear how much better you feel. But what about some acknowledgement of the general long-term risks of your current diet? Just to keep things balanced, it might help to mention what can be done to track such risks, and how to resolve any conflicts between risk analyses and current feelings of well-being.

For the second issue, we hear about personal experiences that led you to regard Teicholz’s book favourably (it made sense to you both physiologically as well as in terms of personal history). This is a powerful narrative strategy that also discloses your non-expert take on it all. But it seems to me overall that you talk about personal experience as if it could legitimate ignoring scientific consensus. The post could easily be interpreted as encouraging readers to look for explanations (funding, corruption etc) that must have enabled false beliefs to dominate that consensus, rather than understanding this as a story of how tools and data and models changed. It’s not clear to me there’s anything special about this case of scientific change versus others.

As you note, it would be very valuable for ‘someone from the other side’ to sum up in a balanced way the evidence for and against certain positions, and to state very clearly the evidential factors that led to the remodelling or even replacement of that consensus. But more immediately, in a post like this, it would help to mention disputes about Teicholz’s analyses of dietary research (e.g., https://cspinet.org/letter-requesting-bmj-retract-investigation). The way you’ve framed this could be read as your personal experience vindicating certain scientific findings, which are then themselves exempt from further questions. This is worrying because of how easily nutritional science gets overwhelmed by fads, bodily intuitions, and lack of knowledge.

The update to your blog post is very useful, because it shows there’s something crucial about diet that is still not understood in relation to disorders such as diabetes. The study the update mentions shows that any diet that achieves weight loss helps counteract diabetes. This is enormously valuable information. For it to be dismissed as ‘weak support for carbohydrates’ misses the point of what the study reveals.

Even now, it would seem, we know far too little about connections between food intake, physiological states, and disease outcomes. For this, many more systematic studies of long-term interventions are needed, plus all the fine-grained mechanistic work that can explain dietary outcomes. It would be great to have some follow-up posts that offer some further depth to this debate and illuminate our understanding of metazoans at the same time.

Disclosure: I am a long-term vegetarian, totally ignorant about whether my diet makes me feel better or worse than I’d otherwise be. I think of my diet as more of a habit than a nutritional conviction but even so, find it extremely difficult even to contemplate eating meat.

I take these issues seriously and appreciate their being raised. Specifically, Maureen is concerned that I am letting my own experiences with different diets affect how I write about a scientific controversy, both because short-term benefits are different from long-term health and because personal perspectives should have little weight when considering studies based on large amounts of data.

In the post I emphasized my own case for a few reasons, but one was its making explicit the fact that I am not writing from the viewpoint of an expert; no one should look to me for an expert opinion on these matters. I am wading my way through some of the primary literature, but I’ve not waded nearly far enough to present a judgment. Teicholz certainly has worked through a lot of the literature; the book is a long piece of investigative journalism, not just ordinary reporting or informal opining. I’d not have written the post if I didn’t find a lot of what she says pretty convincing.

I’ll reply to a couple of Maureen’s specific points.

1. “[I]t’s still immensely unclear whether there are long-term benefits to low-carbohydrate diets.” In response: I accept that. One thing that does concern me in these discussions is the following tendency. People say: “We really don’t know… we need more data… So you should stick with a high-carb diet for now.” I take it the tension there is obvious (and I don’t suggest that Maureen is saying that). If we really don’t know, then giving that advice looks like a mere attempt to say something reassuring. The quote from the diabetes doctor I included in my “Update” above has some of that flavor.

2. “The study the update mentions shows that any diet that achieves weight loss helps counteract diabetes. This is enormously valuable information. For it to be dismissed as ‘weak support for carbohydrates’ misses the point of what the study reveals.” In response: I think both points are important. It’s important that weight control seems so pivotal, however that weight loss is achieved. It’s also important that the findings reported in the New York Times article do not provide any sort of rebuttal to the people who said “Try a low carb diet for diabetes.” The Kolata piece does not support a return to the status quo (lose weight but avoid fat). Instead the upshot is: all those diets seem to be on a par at this stage, as far as diabetes goes, so choose whatever helps you lose weight.

3. “[I]t would help to mention disputes about Teicholz’s analyses of dietary research (e.g., https://cspinet.org/letter-requesting-bmj-retract-investigation). The way you’ve framed this could be read as your personal experience vindicating certain scientific findings, which are then themselves exempt from further questions.” In response: It’s certainly true that Teicholz’s work has been rejected by many professionals. I did, before posting, have a look at that controversy around her BMJ article. (She wrote an article here that led to well over a hundred professionals calling on the journal to retract it, based on 11 alleged errors.) Teicholz has written a couple of replies, and the journal published accepted one correction here. Her own website says that the journal, some time ago, said they would consider whether a retraction is appropriate, and they have not yet issued a decision [* update: there will be no retraction]. I’ve not worked through enough of the back and forth – there are accusations in both directions – to make my own call on it.

4. “The way you’ve framed this could be read as your personal experience vindicating certain scientific findings, which are then themselves exempt from further questions. This is worrying because of how easily nutritional science gets overwhelmed by fads, bodily intuitions, and lack of knowledge.” I appreciate this point. In response, I have to be frank: it’s hard to ignore the messages one’s getting from one’s body – how one feels in a large scale way. The before-and-after in 1998 was dramatic. This was not just a matter of intuitions, but a question of whether I was well enough to function in my job. I’ll try to ignore the messages from my body if the science telling me to do so is rock solid. But the science giving me those orders does not look at all like that.